Method of manufacturing a semiconductor device

ABSTRACT

The improvement of the yields of semiconductor devices is intended. In a method for manufacturing a semiconductor device, it has forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin from a first side to a second side of a main surface of the substrate, the plurality of semiconductor chips being mounted on the main surface of the substrate from the first side to the second side of the main surface with a predetermined space, the second side facing to the first side, the method further has applying cleaning treatment to the main surface of the substrate before forming the resin enclosure.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a technique of manufacturing a semiconductor device, particularly to an effective technique suitable for being applied to a technique of manufacturing a semiconductor device adopting block molding by transfer molding.

[0003] 2. Description of the Related Art

[0004] In semiconductor device manufacturing, a manufacturing method is known in which a plurality of semiconductor chips mounted on a main surface of a substrate is block-molded with one resin enclosure and then the resin enclosure and the substrate are simultaneously separated into each of the semiconductor chips (each of products). This manufacturing method is disclosed in Japanese patent Laid-Open No. 107161/1996 (U.S. Pat. No. 5,729,437) (publicly known document 1) and Japanese patent Laid-Open No. 12578/2000 (U.S. Pat. No. 6,200,121) (publicly known document 2), for example. Additionally, the publicly known document 1 discloses a method for forming a resin enclosure for block molding by potting and the publicly known document 2 discloses a method for forming a resin enclosure for block molding by transfer molding.

SUMMARY OF THE INVENTION

[0005] The inventors studied the method for forming a resin enclosure for block molding by transfer molding (hereafter, it is called block transfer molding). Consequently, they found the following problems.

[0006]FIGS. 23A to 26B depict diagrams illustrating resin flows when a resin enclosure is formed by block transfer molding in traditional semiconductor device manufacturing (A shows a schematically plan view and B shows a schematically sectional view). In FIGS. 23A to 26B, 60 denotes a substrate, 60X denotes a main surface of the substrate 60, 61 denotes a semiconductor chip, 62 denotes a molding die, 62A denotes an upper mold of the molding die 62, 62B denotes an under mold of the molding die 62, 63 denotes a cavity, 64 denotes a gate, 65 denotes a runner, 66 denotes an air vent, 67A denotes a resin, 67B denotes a void and S denotes a resin injecting direction.

[0007] Block transfer molding is adopted in manufacturing a BGA (Ball Grid Array) semiconductor device and a CSP (Chip Size Package or Chip Scale Package) semiconductor device having a package structure with a substrate. In manufacturing these types of semiconductor devices, the substrate 60 where a plurality of product forming areas 60A are arranged on the main surface 60X in matrix with a predetermined space is used as shown in FIG. 23A. Therefore, a plurality of semiconductor chips 61 mounted on the substrate 60 are also arranged in matrix with a predetermined space.

[0008] In block transfer molding, the molding die 62 having the cavity 63, the gates 64, the runners 65, cull (not shown), pots (not shown) and the air vents 66 is used as shown in the same drawing. The resin 67A is injected inside the cavity 63 from the pots through the culls, the runners 65 and the gates 64.

[0009] As the substrate 60, since that has a rectangular plane is generally used, the plane shape of the cavity 63 is also formed into a rectangular shape corresponding to this. In this case, a plurality of gates 64 is disposed along one of two long sides facing each other of the cavity 63 so as to evenly fill the resin 67A inside the entire cavity 63. Thus, the resin 67A is injected inside the cavity 63 from one long side to the other long side of the substrate 60.

[0010] The resin 67A thus injected inside the cavity 63 flows from one long side to the other long side of the substrate 60 as shown in FIGS. 23A to 25B, and is filled inside the cavity 63 as shown in FIGS. 26A and 26B.

[0011] Meanwhile, the resin 67A that has been injected inside the cavity 63 flows along a main surface and the side surfaces of the semiconductor chip 61. The resin 67A flowing along the main surface and the side surfaces of the semiconductor chip 61 runs into between the semiconductor chips 61. However, the resin 67A flowing along the main surface of the semiconductor chip 61 is prevented from running by the semiconductor chip 61. Therefore, it runs slower than the resin 67A flowing along the side surfaces of the semiconductor chip 61. On this account, voids 67B are generated at positions where the resin 67A flowing along the main surface of the semiconductor chip 61 meets the resin 67A flowing along the side surfaces of the semiconductor chip 61 (see FIGS. 25A and 25B). The voids 67B gradually become smaller as they are moved by the flow of the resin 67A in the resin injecting process. However, voids 67C remain at positions hiding behind the semiconductor chips 61 with respect to the injecting direction S of the resin 67A (see FIGS. 26A and 26B). In transfer molding, there is conducted a process for reducing voids that have been caught in the resin by applying a pressure higher than that in injection after resin filling is complete. However, the voids 67C are considerably greater than voids that do not cause the popcorn phenomenon when temperature cycle testing even though this process is applied. Thus, they become a factor that reduces the yields of semiconductor devices.

[0012] The aforementioned publicly known document 1 (Japanese patent Laid-Open No. 107161/1996) discloses the use of a molding material having a low thixotropic property and further combining vacuum defoaming as a means of preventing the generation of unfilled portions. However, in transfer molding, applying the aforesaid means cannot solve the problem of the void generation.

[0013] When transfer molding is adopted, the resin flow is to be controlled by injection from the gates. Therefore, the air vents are disposed at positions facing to the gates and in areas where the resin is finally filled, and thereby air inside the cavity can be removed from the air vents until the resin is filled inside the cavity.

[0014] However, in transfer molding, when the thixotropic property is reduced to the extent that the resin flow is governed by the thixotropic property or a resin injecting rate is decreased, it becomes difficult to control the resin flow and it becomes substantially impossible to set the positions of the air vents that have to be disposed in the areas where the resin is finally filled.

[0015] Accordingly, in transfer molding, it is virtually impossible to control the conditions of a resin in the injecting process and to eliminate void catching by adopting a material having a low thixotropic property as the resin.

[0016] Additionally, when a great amount of a filler (80% or more, for example) is added to a molding resin for a purpose of reducing warpage due to the cure shrinkage of the molding resin to facilitate the dicing process or of having a thermal expansion coefficient of a resin closer to that of a semiconductor chip to reduce stress applied to the semiconductor chip when heat cycling, the existence of the filler increases the thixotropic property even though those having a low thixotropic property are adopted as a molding maerial. Therefore, a low thixotropic propertiy to the extent of solving void catching cannot be obtained.

[0017] Furthermore, in potting, a method such as vacuum defoaming can be adopted in which air bubbles are removed outside a resin by placing semiconductor devices in a state of the resin not being cured in a low-pressure atmosphere after potting. However, in transfer molding, resin injection and curing are performed inside the cavity and thus the method for reducing voids by vacuum defoaming cannot be adopted.

[0018] Consequently, in transfer molding, applying techniques described in the publicly known document 1 cannot prevent the void generation. Therefore, new methods need to be adopted for voids.

[0019] Then, the inventors turned their attention to the wettability of the resin 67A to the main surface of the substrate 60 to invent the invention because the voids 67C contact and remain on the main surface of the substrate 60 as shown in FIGS. 26A and 26B.

[0020] The purpose of the invention is to provide techniques capable of improving the yields of semiconductor devices.

[0021] The aforementioned purpose, the other purposes and new features of the invention will be apparent from the description of the specification and the accompanying drawings.

[0022] Among the inventions to be disclosed in the application, the following is the brief description of the summary of a representative one.

[0023] (1) A method for manufacturing a semiconductor device comprises forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside the cavity from a first side to a second side of a main surface of a substrate, the plurality of semiconductor chips being mounted on the main surface of the substrate from the first side to the second side of the main surface with a predetermined space, the second side facing to the first side,

[0024] wherein the method further comprises removing impurities remaining on the main surface of the substrate before forming the resin enclosure.

[0025] Removing impurities remaining on the main surface of the substrate is performed by plasma cleaning.

[0026] (2) A method for manufacturing a semiconductor device comprises forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside the cavity from a first side to a second side of a main surface of a substrate, the plurality of semiconductor chips being mounted on the main surface of the substrate from the first side to the second side of the main surface with a predetermined space, the second side facing to the first side,

[0027] wherein the method further comprises surface roughening treatment is applied to the main surface of the substrate before forming the resin enclosure.

[0028] The surface roughening treatment is performed by plasma cleaning.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The teachings of the invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:

[0030]FIGS. 1A and 1B depict diagrams illustrating a schematic configuration of a semiconductor device of an embodiment 1 of the invention (FIG. 1A is a schematic plan view in a state that a resin enclosure is removed and FIG. 1B is a schematically sectional view along a line a-a shown in FIG. 1A);

[0031]FIG. 2 depicts a schematically sectional view enlarging a part of FIG. 1B;

[0032]FIG. 3 depicts a schematically plan view of a substrate (a substrate for separation) for use in fabricating the semiconductor device of the embodiment 1;

[0033]FIG. 4 depicts a schematically plan view enlarging a part of FIG. 3;

[0034]FIG. 5 depicts a schematically sectional view along a line b-b shown in FIG. 4;

[0035]FIG. 6 depicts a schematically plan view illustrating a schematic configuration of an upper mold of a molding die for use in fabricating the semiconductor device of the embodiment 1;

[0036]FIG. 7 depicts a schematically plan view illustrating schematic configuration of an under mold of the molding die for use in fabricating the semiconductor device of the embodiment 1;

[0037]FIG. 8 depicts a schematically sectional view illustrating a schematic configuration of the molding die for use in fabricating the semiconductor device of the embodiment

[0038]FIGS. 9A and 9B depict schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 1;

[0039]FIGS. 10A and 10B depict schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 1;

[0040]FIG. 11 depicts a schematically sectional view for describing the fabrication of the semiconductor device of the embodiment 1;

[0041]FIGS. 12A and 12B depict diagrams for describing the resin molding process in fabricating the semiconductor device of the embodiment 1 (FIG. 12A is a schematically plan view and FIG. 12B is a schematically sectional view);

[0042]FIGS. 13A and 13B depict diagrams for describing the resin molding process in fabricating the semiconductor device of the embodiment 1 (FIG. 13A is a schematically plan view and FIG. 13B is a schematically sectional view);

[0043]FIGS. 14A and 14B depict diagrams for describing the resin molding process in fabricating the semiconductor device of the embodiment 1 (FIG. 14A is a schematically plan view and FIG. 14B is a schematically sectional view);

[0044]FIGS. 15A and 15B depict diagrams for describing the resin molding process in fabricating the semiconductor device of the embodiment 1 (FIG. 15A is a schematically plan view and FIG. 15B is a schematically sectional view);

[0045]FIGS. 16A and 16B depict schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 1;

[0046]FIG. 17 depicts a schematically sectional view illustrating a schematic configuration of a semiconductor device of an embodiment 2 of the invention;

[0047]FIGS. 18A and 18B depict schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 2;

[0048]FIGS. 19A and 19B depict schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 2;

[0049]FIG. 20 depicts a schematically sectional view illustrating a schematic configuration of a semiconductor device of an embodiment 3 of the invention;

[0050]FIGS. 21A and 21B depicts schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 3;

[0051]FIGS. 22A and 22B depicts schematically sectional views for describing the fabrication of the semiconductor device of the embodiment 3;

[0052]FIGS. 23A and 23B depict diagrams for describing the rein molding process in fabricating an orthodox semiconductor device (FIG. 23A is a schematically plan view and FIG. 23B is a schematically sectional view);

[0053]FIGS. 24A and 24B depict diagrams for describing the rein molding process in fabricating the orthodox semiconductor device (FIG. 24A is a schematically plan view and FIG. 24B is a schematically sectional view);

[0054]FIGS. 25A and 25B depict diagrams for describing the rein molding process in fabricating the orthodox semiconductor device (FIG. 25A is a schematically plan view and FIG. 25B is a schematically sectional view); and

[0055]FIGS. 26A and 26B depict diagrams for describing therein molding process in fabricating the orthodox semiconductor device (FIG. 26A is a schematically plan view and FIG. 26B is a schematically sectional view).

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0056] Hereafter, the embodiments of the invention will be detailedly described in reference with the drawings. Additionally, in all the drawings for describing the embodiments, those having the same functions are designated the same numerals and signs, omitting the repeated description.

[0057] (Embodiment 1)

[0058] In this embodiment, an example where the invention is applied to the BGA semiconductor device will be described.

[0059]FIGS. 1A and 1B depict diagrams illustrating a schematic configuration of the semiconductor device of an embodiment 1 of the invention (FIG. 1A is a schematic plan view in a state that a resin enclosure is removed and FIG. 1B is a schematically sectional view along a line a-a shown in FIG. 1A), and FIG. 2 depicts a schematically sectional view enlarging a part of FIG. 1B.

[0060] As shown in FIGS. 1A, 1B and 2, a semiconductor device 1A of the embodiment is configured to mainly have a substrate (circuit board) 2, a semiconductor chip 10, a plurality of bonding wires 13, a resin enclosure 14 and a plurality of projecting electrodes 15. The semiconductor chip 10 and the plurality of bonding wires 13 are encapsulated with the resin enclosure 14.

[0061] The semiconductor chip 10 is attached and fixed to a main surface 2X of the substrate 2 through a bonding layer 12, the main surface 2X (chip mounting surface) faces to the other main surface (back surface) 2Y of the substrate 2. A plane shape of the semiconductor chip 10 is formed to have a rectangular shape; it is formed to have a square shape in the embodiment, for example. The semiconductor chip 10 is configured to have a semiconductor substrate made of monocrystal silicon, multilevel interconnection layers having a plurality of insulating layers and wiring layers laminated on the circuit forming side of the semiconductor substrate, and a surface protecting film deposited to cover the multilevel interconnection layers, for example. As the surface protecting film, a polyimide resin is used, for instance.

[0062] The semiconductor chip 10 is incorporated with a control circuit, for example, as an integrated circuit. The control circuit is mainly configured of transistor devices formed on the circuit forming surface of the semiconductor substrate and wirings formed in the wiring layers.

[0063] A plurality of electrode pads (bonding pads) 11 are formed on a main surface 10X of the semiconductor chip 10 along each of the sides around the semiconductor chip 10, the main surface 10X (circuit forming surface) faces the other main surface (back surface) of the semiconductor chip 10. Each of the plurality of electrode pads 11 is formed on the topmost wiring layer among the multilevel interconnection layers of the semiconductor chip 10, which is electrically connected to the transistor devices constituting the control circuit. Each of the plurality of electrode pads 11 is formed of a metal film such as an aluminium (Al) film or aluminium alloy film.

[0064] The substrate 2 is not shown in detail, but it has a multilevel interconnection structure where each of insulating layers and conductive layers is sequentially laminated. Each of the insulating layers is formed of a glass-epoxy substrate where glass fibers are impregnated with an epoxy resin and each of wiring layers is formed of a metal film made of copper (Cu), for example. The plane shape of the substrate 2 is formed to have a rectangular shape; it is formed to have a square shape in the embodiment, for example.

[0065] The main surface 2X of the substrate 2 is disposed with a plurality of connecting parts (lands) 3 made of a part of wirings formed in the topmost conductive layer thereof. Additionally, a resin film 4 for protecting the wirings formed in the topmost conductive layer thereof is deposited on the main surface 2X of the substrate 2. The resin film 4 is formed with apertures for exposing the surfaces of the connecting parts 3.

[0066] The back surface 2Y of the substrate 2 is disposed with a plurality of electrode pads (lands) 5 made of a part of wirings formed in the undermost conductive layer thereof. Furthermore, the back surface 2Y of the substrate 2 is deposited with a resin film 6 for protecting the wirings formed in the undermost conductive layer thereof. The resin film 6 is formed with apertures for exposing the surfaces of the electrode pads 5. The resin films 4 and 6 are formed of an epoxy resin or polyimide resin, for example.

[0067] Each of the plurality of bump electrodes 15 is fixed to the plurality of electrode pads 5 disposed on the back surface 2Y of the substrate 2, which is electrically and mechanically connected. The projecting electrode 15 is formed of a ball-like bump made of a solder material having Pb—Sn composition, for example.

[0068] The plane shape of the resin enclosure 14 is formed to have a rectangular shape; it is formed to have a square shape in the embodiment, for example. The resin enclosure 14 is formed of an epoxy thermosetting insulating resin added with a phenol curing agent, a silicon rubber and many fillers (silica, for example) for the purpose of intending to have a low stress.

[0069] Each of the plurality of electrode pads 11 disposed on the main surface 10X of the semiconductor chip 10 is electrically connected to the plurality of connecting parts 3 disposed on the main surface 2X of the substrate 2 through the bonding wires 13. As the bonding wires 13, gold (Au) wires are used, for example. As a method for connecting the bonding wires 13, boll bonding (nail head bonding) that combines thermo-compression bonding with ultrasonic vibration is used.

[0070] The resin enclosure 14 and the substrate 2 have almost the same outer shapes and sizes, and the side surfaces of the resin enclosure 14 and the substrate 2 are flushed. In fabricating the semiconductor device 1A of the embodiment, a fabricating method is adopted in which a plurality of semiconductor chips 10 mounted on the main surface of the substrate with a predetermined space is block-molded with a resin enclosure and then the resin enclosure and the substrate are simultaneously separated into each of the semiconductor chips 10 (each of product forming areas), the method will be described later.

[0071]FIG. 3 depicts a schematically plan view illustrating a substrate for use in fabricating the semiconductor device 1A of the embodiment. FIG. 4 depicts a schematically plan view enlarging a part of FIG. 3. FIG. 5 depicts a schematically sectional view along a line b-b shown in FIG. 4.

[0072] As shown in FIGS. 3 to 5, the plane of a substrate (circuit board) 20 is formed to have a rectangular shape; it is formed to have a rectangular shape in the embodiment, for example. On a main surface (chip mounting surface) 20X of the substrate 20, a plurality of product forming areas 22 are arranged in matrix with a predetermined space. Each of the product forming areas 22 is disposed with a chip mounting area 23 and a plurality of connecting parts 3 are arranged therearound. Each of the product forming areas 22 is disposed in a molding area 21 where a resin enclosure is formed. Each of the product forming areas 22 is configured to have the same configuration as the substrate 2. That is, a resin film 4 is deposited over the entire main surface 20X of the substrate 20 and a resin film 6 is deposited over the entire other main surface (back surface) facing to the main surface 20X. Additionally, each of the product forming areas 22 is spaced each other through a separation area for separating the substrate 20.

[0073]FIG. 6 depicts a schematically plan view illustrating a schematic configuration of an upper mold of a molding die for use in fabricating the semiconductor device 1A of the embodiment. FIG. 7 depicts a schematically plan view illustrating a schematic configuration of an under mold of the molding die. FIG. 8 depicts a schematically sectional view illustrating a schematic configuration of the molding die.

[0074] As shown in FIGS. 6 to 8, a molding die 30 has a cavity 31, a plurality of gates 32, a plurality of subrunners 33, a plurality of main runners 34, a plurality of culls 35, a joining runner 36, a plurality of air vents 37, a plurality of pots 38 and a substrate mounting area 39. Each of the component parts 31 to 37 is disposed in an upper mold 30A and each of the component parts 38 and 39 is disposed in an under mold 30B. The plane shapes of the cavity 37 and the substrate mounting area 39 are formed to have a plane shape corresponding to the plane shape of the substrate 20; they are formed to have a rectangular shape in the embodiment, for example. The cavity 31 is recessed from the mating face of the upper mold 30A in the depth direction. The substrate mounting area 39 is recessed from the mating face of the under mold 30B in the depth direction.

[0075] In the molding die 30, a resin is injected inside the cavity 31 from the pots 38 through the culls 35, the main runners 34, the subrunners 33 and the gates 32. The plurality of gates 32 are arranged along one of two long sides of the cavity 31 corresponding each other so as to evenly fill the resin inside the entire cavity 31. Thus, the resin is injected inside the cavity 31 from one long side to the other long side of the cavity 31. The plurality of air vents 37 are arranged along three sides except the long side of the cavity 31 where the gates 32 are disposed.

[0076] Next, the fabrication of the semiconductor device 1A of the embodiment will be described with reference to FIGS. 9 to 16. FIGS. 9, 10, 11 and 16 depict schematically sectional views for describing the fabrication of the semiconductor device. FIGS. 12 to 15 depict diagrams illustrating a resin flow when a resin enclosure is formed by block transfer molding (A is a schematically plan view and B is a schematically sectional view).

[0077] First, the substrate 20 shown in FIG. 3 is prepared.

[0078] Then, a bonding layer 12 made of an epoxy thermosetting resin, for example, is deposited on the chip mounting area in each of the product forming areas on the main surface 20X of the substrate 20. The semiconductor chip 10 is mounted on each of the chip mounting areas through the bonding layer 12. Heat treatment is applied to cure the bonding layer 12. The semiconductor chip 10 is attached and fixed in each of the chip mounting areas as shown in FIG. 9A. In this process, the substrate 20 is heated at temperature of about 150° C., for example, and therefore a natural oxide film is formed on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 20. Additionally, impurities such as fats, oils and organic solvents contained in the resin film 4 are outgassed to contaminate the main surface 20X and the surfaces of the connecting parts 3 of the substrate 20 and the surfaces of electrode pads 11.

[0079] Subsequently, as shown in FIG. 9B, cleaning treatment is applied to the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 20 to remove impurities such as the natural oxide film, fats, oils and organic solvents remaining on these surfaces. The cleaning treatment is performed by plasma cleaning using an oxygen or argon gas, for example.

[0080] Then, as shown in FIG. 10A, the electrode pads 11 of the semiconductor chip 10 are electrically connected to the connecting parts 3 of the substrate 20 with the bonding wires 13. In this process, impurities such as the natural oxide film, fats, oils and organic solvents remaining on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 20 have been removed in the previous cleaning process and thus the connection reliability in the wire bonding process is enhanced. Furthermore, in this process, the substrate 20 is heated at temperature of about 125° C., for example. Thus, impurities such as fats, oils and organic solvents contained in the resin film 4 are outgassed to contaminate the main surface 20X of the substrate 20. Moreover, in this process, a plurality of semiconductor chips 10 are mounted on the main surface 20X of the substrate 20.

[0081] Subsequently, as shown in FIG. 10B, cleaning treatment is applied to the main surface 20X of the substrate 20 to remove impurities such as fats, oils and organic solvents remaining on the main surface 20X of the substrate 20. This cleaning treatment is performed by plasma cleaning using an oxygen or argon gas. Plasma cleaning can remove impurities such as fats and oils and can roughen the surface of the main surface 20X of the substrate 20.

[0082] Then, as shown in FIG. 11, the substrate 20 is positioned between the upper mold 30A and the under mold 30B of the molding die 30 and the plurality of semiconductor chips 10 mounted on the main surface 20X of the substrate 20 are placed inside the cavity 31 of the molding die 30 along with the substrate 20. At this time, the substrate 20 is mounted on the substrate mounting area 39 disposed in the under mold 30B.

[0083] Subsequently, an epoxy thermosetting resin, for example, is injected inside the cavity 31 from the pods 38 through the culls 35, the main runners 34, the subrunners 33 and the gates 32 to form a resin enclosure 24 for block-molding the plurality of semiconductor chips 10 mounted on the main surface 20X of the substrate 20.

[0084] In this process, as shown in FIG. 12A, the plurality of gates 32 are arranged along one of two long sides of the cavity 31 facing each other so as to evenly fill a resin 24A inside the entire cavity 31 and therefore the resin 24A is injected inside the cavity 31 from one long side to the other long side of the substrate 20. At this time, the semiconductor chips 10 are arranged so that two sides facing each other are almost orthogonal to the injecting direction S of the resin 24A.

[0085] The resin 24A injected inside the cavity 31 flows from one long side to the other long side of the substrate 20 as shown in FIGS. 12A to 14B and is filled inside the cavity 31 as shown in FIGS. 15A and 15B.

[0086] The resin 24A injected inside the cavity 31 flows along the main surface 10X and the side surfaces of the semiconductor chip 10. The resin 24A flowing along the main surface 10X and the side surfaces of the semiconductor chip 10 runs into between the semiconductor chips 10. However, the resin 24A flowing along the main surface 10X of the semiconductor chip 10 runs slower than the resin 24A flowing along the side surfaces of the semiconductor chip 10. Therefore, voids 24B are generated at positions where the resin 24A flowing along the main surface 10X of the semiconductor chip 10 meets the resin 24A flowing along the side surfaces of the semiconductor chip 10 (see FIGS. 14A and 14B). On the other hand, impurities such as fats and oils remaining on the main surface 20X of the substrate 20 have been removed in the aforesaid cleaning process and the main surface 20X of the substrate 20 is further roughened. Thus, the wettability of the resin 24A is enhanced with respect to the main surface 20X of the substrate 20. On this account, the resin 24A flowing along the side surfaces of the semiconductor chip 10 is allowed to easily enter the positions hiding behind the semiconductor chips 10 with respect to the injecting direction S of the resin 24A. Accordingly, the voids 24B generated at the positions where the resin 24A flowing along the main surface 10X of the semiconductor chip 10 meets the resin 24A flowing along the side surfaces of the semiconductor chip 10 (see FIGS. 14A and 14B) are removed from the main surface 20X of the substrate 20. The voids 24B thus removed from the main surface 20X of the substrate 20 are allowed to easily move by the flow of the resin 24A in the resin injecting process. Therefore, the voids 24B do not remain at the positions hiding behind the semiconductor chips 10 as shown in FIG. 15A and 15B. The voids 24B removed from the main surface 20X of the substrate 20 become smaller and smaller by the flow of the resin 24A as they move. They become smaller to the extent of not causing the popcorn phenomenon when temperature cycle testing.

[0087] That is, cleaning treatment is applied to the main surface 20X of the substrate 20 to remove impurities such as fats and oils remaining on the main surface 20X of the substrate 20 before forming the resin enclosure 24. Thereby, the wettability of the resin 24A to the main surface 20X of the substrate 20 is enhanced and the resin 24A flowing along the side surfaces of the semiconductor chip 10 is allowed to easily enter the positions hiding behind the semiconductor chips 10 with respect to the injecting direction S of the resin 24A. Thus, the voids 24B generated at the positions where the resin 24A flowing along the main surface lox of the semiconductor chip 10 meets the resin 24A flowing along the side surfaces of the semiconductor chip 10 are removed from the main surface 20X of the substrate 20.

[0088] Additionally, cleaning treatment is performed by plasma cleaning and thereby the main surface 20X of the substrate 20 is roughened as well as impurities such as fats and oils remaining on the main surface 20X of the substrate 20 are removed. Therefore, the wettability of the resin 24A with respect to the main surface 20X of the substrate 20 is further enhanced. The wettability of the resin 24A is enhanced by removing impurities such as fats and oils remaining on the surface where the resin flows and by roughening the surface where the resin flows. However, naturally, the enhancement of the wettability of the resin by surface roughening is limited.

[0089] Then, as shown in FIG. 16A, projecting electrodes 15 are formed on the surfaces of electrode pads 5 disposed on the back surface of the substrate 20 by ball feeding, for example. Then, the substrate 20 is attached and fixed to a dicing sheet 25 so that the resin enclosure 24 block-molded faces to the dicing sheet 25. After that, as shown in FIG. 16B, the resin enclosure 24 and the substrate 20 are simultaneously separated into each of semiconductor chips 10 (each of the product forming areas). The semiconductor device 1A shown in FIGS. 1A to 3 is almost complete in this process.

[0090] In this manner, according to the embodiment, the following effects can be obtained.

[0091] In the method for manufacturing the semiconductor device 1A, the method comprises forming the resin enclosure 24 for block-molding the plurality of semiconductor chips 10 by placing the plurality of semiconductor chips 10 inside the cavity 31 of the molding die 30 along with the substrate 20 and then injecting the resin 24A inside the cavity 31 from one long side to the other long side of the main surface 20X of the substrate 20, the plurality of semiconductor chips 10 being mounted on the main surface 20X of the substrate 20 from one long side to the other long side of the main surface 20X with a predetermined space, the other long side facing to one long side, wherein the method further comprises removing impurities remaining on the main surface 20X of the substrate 20 by plasma cleaning before forming the resin enclosure 24.

[0092] Accordingly, impurities such as fats, oils and organic solvents remaining on the main surface 20X of the substrate 20 are removed, a material having a high wettability to the resin 24A is more exposed on the main surface 20X of the substrate 20 or the main surface 20X of the substrate 20 is formed to have fine bumps and dips. Thereby, the wettabiliry of the resin 24A to the main surface 20X of the substrate 20 is enhanced and the flow accompanying the injection of the resin 24A can accelerate the removal of the voids in the resin 24A. Consequently, the improvement of the yields of the semiconductor devices 1A can be intended.

[0093] Additionally, the example where the substrate 20 having the resin film 4 on the main surface 20X is used was described in the embodiment. However, resin substrates allow impurities such as fats, oils and organic solvents contained in the resin substrates to be outgassed by heat treatment in the fabricating process, even though the main surface 20X does not have the resin film 4.

[0094] Furthermore, the example where a glass-epoxy substrate is used as the substrate 20 was described, but the invention is also effective when a substrate made of BT resin is used.

[0095] Besides, when resin tape is used as the substrate 20, warpage is intensified due to the cure shrinkage of the resin enclosure and thus an amount of a filler added has to be increased. In such a case, voids tend to be generated because the flowability of the resin is decreased.

[0096] (Embodiment 2)

[0097]FIG. 17 depicts a schematically sectional view of a semiconductor device of an embodiment 2 of the invention.

[0098] As shown in FIG. 17, a semiconductor device 1B of the embodiment 2 is basically configured to have the same configuration as the aforesaid embodiment 1, which varies the following configuration.

[0099] That is, a semiconductor chip 10 is attached and fixed to a main surface 2X of a substrate 2 through a bonding layer 12 and a semiconductor chip 40 is attached and fixed to a main surface 10X of the semiconductor chip 10 through a bonding layer 42. The semiconductor chip 40 is formed to have a plane size smaller than that of the semiconductor chip 10. Electrode pads 41 arranged on a main surface of the semiconductor chip 40 are electrically connected to connecting parts 3 formed on a main surface 2X of the substrate 2 through bonding wires 43. The semiconductor chips 10 and 40 are encapsulated by a resin enclosure 14.

[0100] Hereafter, the manufacture of the semiconductor device 1B will be described with reference to FIGS. 18A to 19B. FIGS. 18A to 19B depict schematically sectional views for describing the manufacture of the semiconductor device.

[0101] First, a substrate 20 is prepared. Then, the bonding layer 12 made of an epoxy thermosetting resin, for example, is deposited on a chip mounting area in each of product forming areas on a main surface 20X of the substrate 20. A semiconductor chip 10 is mounted on the chip mounting area through the bonding layer 12. Heat treatment is applied to cure the bonding layer 12 and the semiconductor chip 10 is attached and fixed in the chip mounting area. In this process, the substrate 20 is heated at temperature of about 180° C., for example, and thus a natural oxide layer is deposited on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 20. Additionally, impurities such as fats, oils and organic solvents contained in a resin film 4 are outgassed to contaminate the main surface of the substrate 20, and the surfaces of the connecting parts 3 and the electrode pads 11.

[0102] Then, the main surface 10X of each of the semiconductor chips 10 is formed with the bonding layer 42 made of an epoxy thermosetting resin. The semiconductor chip 40 is mounted on the main surface 10X of the semiconductor chip 10 through the bonding layer 42. Heat treatment is applied to cure the bonding layer 42. The semiconductor chip 40 is attached and fixed to the semiconductor chip 10 as shown in FIG. 18A. In this process, the substrate 20 is heated at temperature of about 180° C., for example, and thus a natural oxide layer is deposited on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 20. Furthermore, impurities such as fats and oils contained in the resin film 4 are outgassed to contaminate the main surface of the substrate 20 and the surfaces of the connecting parts 3 and the electrode pads 11.

[0103] Subsequently, as shown in FIG. 18B, the impurities remaining on the surfaces of the electrode pads 11 and 41 of the semiconductor chips 10 and 40 and the surfaces of the connecting parts 3 of the substrate 20 are removed by plasma cleaning using an oxygen or argon gas.

[0104] Then, as shown in FIG. 19A, the electrode pads 11 of the semiconductor chip 10 are electrically connected to the connecting parts 3 of the substrate 20 with bonding wires 13 and the electrode pads 41 of the semiconductor chip 40 are electrically connected to the connecting parts 3 of the substrate 20 with the bonding wires 43. In this process, the substrate 20 is heated at temperature of about 125° C., for example, and thus impurities such as fats and oils contained in the resin film 4 are outgassed to contaminate the main surface of the substrate 20.

[0105] Subsequently, as shown in FIG. 19B, the impurities remaining on the main surface 20X of the substrate 20 are removed by plasma cleaning using an oxygen or argon gas. In this process, plasma cleaning can roughen the main surface 20X of the substrate 20 and therefore the removal of impurities and roughening the main surface 20X of the substrate 20 can be performed.

[0106] Then, as similar to the aforementioned embodiment 1, the substrate 20 is positioned between an upper mold 30A and an under mold 30B of a molding die 30. The plurality of semiconductor chips 10 mounted on the main surface 20X of the substrate 20 and each of the plurality of semiconductor chips 40 layered on the respective semiconductor chips 10 are placed inside a cavity 31 of the molding die 30 along with the substrate 20. A resin is then injected inside the cavity 31 from pots 38 through culls 35, main runners 34, subrunners 33 and gates 32. A resin enclosure for block-molding the plurality of semiconductor chips 10 and 40 mounted on the main surface 20X of the substrate 20 is formed.

[0107] After that, the same process as the aforesaid embodiment 1 is applied and thereby the semiconductor device 1B shown in FIG. 17 can be manufactured.

[0108] In manufacturing the semiconductor device 1B of the embodiment 2, two semiconductor chips 10 and 40 are laminated on the main surface 20X of the substrate 20. Thus, voids tend to be generated at the positions hiding behind the semiconductor chips 10 and 40 with respect to the injecting direction S of the resin 24A. However, cleaning treatment is applied to the main surface 20X of the substrate 20 before the resin enclosure is formed and thereby the same effects as the aforementioned embodiment 1 can be obtained.

[0109] (Embodiment 3)

[0110]FIG. 20 depicts a schematically sectional view of a semiconductor device of an embodiment 3 of the invention.

[0111] As shown in FIG. 20, a semiconductor device IC of the embodiment 3 is basically configured to have the same configuration as the embodiment 2, which varies the following configuration.

[0112] That is, a semiconductor chip 50 is mounted on a main surface 2X of a substrate 2 through projecting electrodes 53 and a semiconductor chip 10 is attached and fixed to the other main surface (back surface) facing to one main surface of the semiconductor chip 50 through a bonding layer 12. Electrode pads 51 arranged on the main surface of the semiconductor chip 50 are electrically connected to electrode pads 3A arranged on the main surface 2X of the substrate 2 through the projecting electrodes 53. An epoxy thermosetting resin 52, for example, is filled between the semiconductor chip 50 and the substrate 2. Electrode pads 11 of the semiconductor chip 10 are electrically connected to connecting parts 3 of the substrate 2 through bonding wires 13. The semiconductor chips 50 and 10 are encapsulated by a resin enclosure 14.

[0113] Hereafter, the manufacture of the semiconductor device 1C will be described with reference to FIGS. 21 and 22. FIGS. 21 and 22 depict schematically sectional views for describing the manufacture of the semiconductor device.

[0114] First, the substrate 2 is prepared and then the projecting electrodes 53 are molten in a state in which the projecting electrodes 53 are between the electrode pads 3A arranged in a chip mounting area of each of product forming areas on the main surface 2X of the substrate 2 and the electrode pads 51 arranged on the main surface of the semiconductor chip 50, and the semiconductor chip 50 is mounted on each of the product forming areas on the main surface of the substrate 2. In this process, the substrate 2 is heated at temperature of about 205° C., for example, and thus a natural oxide layer is deposited on the surfaces of the connecting parts 3 of the substrate 2. Additionally, impurities such as fats, oils and organic solvents contained in a resin film 4 are outgassed to contaminate the main surface and the surfaces of the connecting parts 3 of the substrate 2.

[0115] Then, the epoxy thermosetting resin 52, for example, is filled between the semiconductor chip 50 and the substrate 2 and subsequently heat treatment is applied to cure the thermosetting resin 52. In this process, the substrate 2 is heated at temperature of about 150° C., for example, and thus a natural oxide layer is deposited on the surfaces of the connecting parts 3 of the substrate 2. Furthermore, impurities such as fats, oils and organic solvents contained in the resin film 4 are outgassed to contaminate the main surface and the surfaces of the connecting parts 3 of the substrate 2.

[0116] Then, the bonding layer 12 made of an epoxy thermosetting resin, for example, is deposited on the back surface of each of the semiconductor chips 50. The semiconductor chip 10 is mounted on the back surface of the semiconductor chips 50 through the bonding layer 12. Heat treatment is applied to cure the bonding layer 12 and the semiconductor chip 10 is attached and fixed to the semiconductor chip 50 as shown in FIG. 21. In this process, the substrate 2 is heated at temperature of about 180° C., for example, and thus a natural oxide layer is deposited on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 2. Moreover, impurities such as fats and oils contained in the resin film 4 are outgassed to contaminate the main surface of the substrate 2 and the surfaces of the electrode pads 11 and the connecting parts 3.

[0117] Subsequently, as shown in FIG. 21(B), the impurities remaining on the surfaces of the electrode pads 11 of the semiconductor chip 10 and the surfaces of the connecting parts 3 of the substrate 2 are removed by plasma cleaning using an oxygen or argon gas.

[0118] Then, as shown in FIG. 22(A), the electrode pads 11 of the semiconductor chip 10 are electrically connected to the connecting parts 3 of the substrate 2 by bonding wires 13. In this process, the substrate 2 is heated at temperature of about 125° C., for example, and thus impurities such as fats and oils contained in the resin film 4 are outgassed to contaminate the main surface of the substrate 2.

[0119] Subsequently, as shown in FIG. 22(B), the impurities remaining on the main surface 2X of the substrate 2 are removed by plasma cleaning using an oxygen or argon gas. In this process, plasma cleaning can roughen the main surface 2X of the substrate 2 and therefore the removal of impurities and roughening the main surface 2X of the substrate 2 can be performed.

[0120] Then, as similar to the aforementioned embodiment 1, 2, the substrate 2 is positioned between an upper mold 30A and an under mold 30B of a molding die 30. The plurality of semiconductor chips 50 mounted on the main surface 2X of the substrate 2 and each of the plurality of semiconductor chips 10 layered on the respective semiconductor chips 50 are placed inside a cavity 31 of the molding die 30 along with the substrate 2. A resin is then injected inside the cavity 31 from pots 38 through culls 35, main runners 34, subrunners 33 and gates 32. A resin enclosure for block-molding the plurality of semiconductor chips 50 and 10 mounted on the main surface 2X of the substrate 2 is formed.

[0121] After that, the same process as the aforesaid embodiment 1 is applied and thereby the semiconductor device 1C shown in FIG. 20 can be manufactured.

[0122] In manufacturing the semiconductor device 1C of the embodiment 3, two semiconductor chips 50 and 10 are laminated on the main surface 2X of the substrate 2. Thus, voids tend to be generated at the positions hiding behind the semiconductor chips 50 and 10 with respect to the injecting direction S of the resin 24A. However, cleaning treatment is applied to the main surface 2X of the substrate 2 by plasma cleaning before the resin enclosure is formed and thereby the same effects as the aforementioned embodiment 1 can be obtained.

[0123] As described above, the invention made by the inventors has been specifically described in accordance with the embodiments. However, it is needless to say that the invention is not limited to the embodiments, which can be modified variously within a scope of the invention, not deviating the teachings.

[0124] For example, the invention can be applied to a technique of manufacturing a semiconductor device of a CSP structure.

[0125] Additionally, the invention can be applied to a technique of manufacturing a semiconductor device of an MCM structure where a plurality of semiconductor chips are mounted on a substrate.

[0126] In brief, the effect obtained by the representative invention among the inventions disclosed in the application is as follows.

[0127] According to the invention, the improvement of the yields of semiconductor devices can be intended. 

What is claimed is:
 1. A method for manufacturing a semiconductor device comprising forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside said cavity from a first side to a second side of a main surface of said substrate, the plurality of semiconductor chips being mounted on the main surface of said substrate from the first side to the second side of said main surface with a predetermined space, the second side facing to said first side, wherein the method further comprises removing impurities remaining on the main surface of said substrate before forming said resin enclosure.
 2. The method for manufacturing the semiconductor device according to claim 1, wherein removing impurities remaining on the main surface of said substrate is performed by plasma cleaning.
 3. The method for manufacturing the semiconductor device according to claim 2, wherein said plasma cleaning removes impurities remaining on the main surface of said substrate and roughens the main surface of said substrate.
 4. The method for manufacturing the semiconductor device according to claim 1 further comprising mounting said plurality of semiconductor chips on the main surface of said substrate before forming said resin enclosure, wherein removing impurities remaining on the main surface of said substrate is performed after mounting said plurality of semiconductor chips and before forming said resin enclosure.
 5. The method for manufacturing the semiconductor device according to claim 4, wherein mounting said plurality of semiconductor chips includes attaching and fixing said semiconductor chip on the main surface of said substrate and electrically connecting electrode pads formed on a main surface of said semiconductor chip to connecting parts formed on the main surface of said substrate with bonding wires.
 6. The method for manufacturing the semiconductor device according to claim 5 further comprising removing impurities remaining on surfaces of the electrode pads of said semiconductor chip and surfaces of the connecting parts of said substrate by plasma cleaning after attaching and fixing said semiconductor chip and before electrically connecting with said bonding wires.
 7. The method for manufacturing the semiconductor device according to claim 1, wherein said substrate is a resin substrate.
 8. The method for manufacturing the semiconductor device according to claim 1, wherein said substrate has a resin film on the main surface thereof.
 9. The method for manufacturing the semiconductor device according to claim 1, wherein said semiconductor chip is formed to have a rectangular plane, and two sides of said semiconductor chip facing each other are crossed to an injecting direction of said resin.
 10. The method for manufacturing the semiconductor device according to claim 1, wherein said resin is mixed with many fillers.
 11. The method for manufacturing the semiconductor device according to claim 1, wherein said resin is an epoxy thermosetting resin mixed with many fillers.
 12. The method for manufacturing the semiconductor device according to claim 1 further comprising separating said resin enclosure and said substrate into each of said semiconductor chips after forming said resin enclosure.
 13. A method for manufacturing a semiconductor device comprising forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside said cavity from a first side to a second side of a main surface of said substrate, the plurality of semiconductor chips being mounted on the main surface of said substrate from the first side to the second side of said main surface with a predetermined space, the second side facing to said first side, wherein the method further comprises surface roughening treatment is applied to the main surface of said substrate before forming said resin enclosure.
 14. The method for manufacturing the semiconductor device according to claim 13, wherein said surface roughening treatment is performed by plasma cleaning.
 15. The method for manufacturing the semiconductor device according to claim 14, wherein said plasma cleaning removes impurities remaining on a main surface of said substrate and roughens the main surface of said substrate.
 16. The method for manufacturing the semiconductor device according to claim 13 further comprising mounting said plurality of semiconductor chips on the main surface of said substrate before forming said resin enclosure, wherein applying said surface roughening treatment is performed after mounting said plurality of semiconductor chips and before forming said resin enclosure.
 17. The method for manufacturing the semiconductor device according to claim 16, wherein mounting said plurality of semiconductor chips includes attaching and fixing said semiconductor chip on the main surface of said substrate and electrically connecting electrode pads formed on a main surface of said semiconductor chip to connecting parts formed on the main surface of said substrate with bonding wires.
 18. The method for manufacturing the semiconductor device according to claim 17 further comprising applying cleaning treatment to surfaces of the electrode pads of said semiconductor chip and surfaces of the connecting parts of said substrate by plasma cleaning after attaching and fixing said semiconductor chip and before electrically connecting with said bonding wires.
 19. The method for manufacturing the semiconductor device according to claim 13, wherein said substrate is a resin substrate.
 20. The method for manufacturing the semiconductor device according to claim 13, wherein said substrate has a resin film on the main surface thereof.
 21. The method for manufacturing the semiconductor device according to claim 13, wherein said semiconductor chip is formed to have a rectangular plane, and two sides of said semiconductor chip facing each other are crossed in an injecting direction of said resin.
 22. The method for manufacturing the semiconductor device according to claim 13, wherein said resin is mixed with many fillers.
 23. The method for manufacturing the semiconductor device according to claim 13, wherein said resin is an epoxy thermosetting resin mixed with many fillers.
 24. The method for manufacturing the semiconductor device according to claim 13 further comprising separating said resin enclosure and said substrate into each of said semiconductor chips after forming said resin enclosure.
 25. A method for manufacturing a semiconductor device comprising forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of first semiconductor chips and a plurality of second semiconductor chips laminated on each of said plurality of first semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside said cavity from a first side to a second side of a main surface of said substrate, the plurality of first semiconductor chips being mounted on the main surface of said substrate from the first side to the second side of said main surface with a predetermined space, the second side facing to said first side, wherein the method further comprises removing impurities remaining on the main surface of said substrate before forming said resin enclosure.
 26. The method for manufacturing the semiconductor device according to claim 25, wherein removing impurities remaining on the main surface of said substrate is performed by plasma cleaning.
 27. A method for manufacturing a semiconductor device comprising forming a resin enclosure for block-molding a plurality of semiconductor chips by placing a plurality of first semiconductor chips and a plurality of second semiconductor chips laminated on each of said plurality of first semiconductor chips inside a cavity of a molding die along with a substrate and then injecting a resin inside said cavity from a first side to a second side of a main surface of said substrate, the plurality of first semiconductor chips being mounted on the main surface of said substrate from the first side to the second side of said main surface with a predetermined space, the second side facing to said first side, wherein the method further comprises applying surface roughening treatment to the main surface of said substrate before forming said resin enclosure.
 28. The method for manufacturing the semiconductor device according to claim 27, wherein said surface roughening treatment is performed by plasma cleaning. 